When using Claude—whether through the web interface or API calls—you may encounter login failures, error codes, or account issues. This guide compiles the most common Claude error types and their corresponding fixes to help you resume normal use.
Login & Account Access Troubleshooting
If you cannot log into Claude, start by checking your network connection. Some regions may require adjustments to the network environment. Try clearing your browser cache or switching to incognito mode, as cookie conflicts can sometimes cause login loops. Double-check that your account email and password are correct, paying attention to uppercase letters and spaces. If you receive an "Invalid credentials" message, reset your password through the recovery process. If you're stuck on the CAPTCHA step, try a different device or wait a few minutes before retrying.
Common API Error Codes and Their Meanings
A 403 error in the Claude API typically indicates an expired or insufficient API Key permission. Log into the Anthropic console to regenerate a new key. A 429 error means you've exceeded the request rate limit—reduce your request frequency or upgrade your plan. A 503 Service Unavailable error usually points to temporary server overload; wait a few minutes and retry. For a 400 Bad Request error, check the parameter format in your request body, especially the message content field.
